The 14 most expensive skyscrapers built in the last 20 years

Over the last few decades, skyscrapers' heights — and thus their costs — have continued to climb.

Business Insider rounded up the most expensive towers built in the last 20 years, defining a skyscraper as a building that measures at least 500 feet tall. As you will see, not all skyscrapers feature a slender design.

Check them out below, in order from lowest to highest construction cost.

Located in Riyadh, Saudi Arabia, the Kingdom Centre cost approximately $1 billion to build. Construction of the 990-foot skyscraper wrapped up in 2002.

The second floor features a shopping mall, bank, and mosque, designated only for women. Designed by Minnesota-based firm Ellerbe Necket, the Kingdom Centre also includes a hotel, offices, apartments, and a 184-foot skybridge.

The Burj Khalifa in Dubai cost approximately $1.5 billion to build. Construction lasted from 2004 to 2009.

Including the antennae, the tower stands 2,717 feet tall, making it the tallest building in the world. Inside, there are residential apartments, eight hotels, shops, restaurants, and offices. Here's the view from the observation deck (also the world's tallest):

Courtesy of ‘At the Top, Burj Khalifa SKY’

The Seat of the European Central Bank (ECB) in Frankfurt, Germany cost $1.25 billion to construct in 2013.

In the center of the mall, there's a manmade "river" (modeled after the famous one in Venice), where shoppers can take gondola rides.

With a price tag of $3.8 billion, One World Trade Center opened in 2012. Located in New York City, it's next to the site of the original WTC, which is now a memorial for the victims of the September 11 attacks.

The One World Trade Center tower (L) in New York, November 8, 2013.Phil Dolby/Flickr

In the elevator going up to the observation deck, there's a timelapse projection that shows what Manhattan has looked like every year since 1500.

Part of a time-lapse projection of the New York skyline through the years is seen inside the Sky Pod Elevator on the way up to the One World Observatory observation deck on the 100th floor of the One World Trade center tower in New York.Mike Segar/Reuters

In 2010, a set of Las Vegas high-rises called the Cosmopolitan was built for $3.9 billion.

With a price tag of $4.1 billion to construct in 2005, the 614-foot-tall Wynn resort and casino sits on the Las Vegas Strip.

Here's what it looks like inside. In 2016, it started a $1.6 billion expansion, set to be finished in 2020.

Three towers make up the Marina Bay Sands Resort, which opened in 2010 in Singapore.

Wikipedia Commons

With a cost of $5.7 billion, it's billed as one of the world's most expensive casino properties, though it also includes a hotel, a convention center, a mall, a museum, two theaters, seven restaurants, and a skating rink.